/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/ptlrpc/pinger.c
 *
 * Portal-RPC reconnection and replay operations, for use in recovery.
 */

#define DEBUG_SUBSYSTEM S_RPC

#include "../include/obd_support.h"
#include "../include/obd_class.h"
#include "ptlrpc_internal.h"

struct mutex pinger_mutex;
static LIST_HEAD(pinger_imports);
static struct list_head timeout_list = LIST_HEAD_INIT(timeout_list);

struct ptlrpc_request *
ptlrpc_prep_ping(struct obd_import *imp)
{
	struct ptlrpc_request *req;

	req = ptlrpc_request_alloc_pack(imp, &RQF_OBD_PING,
					LUSTRE_OBD_VERSION, OBD_PING);
	if (req) {
		ptlrpc_request_set_replen(req);
		req->rq_no_resend = 1;
		req->rq_no_delay = 1;
	}
	return req;
}

int ptlrpc_obd_ping(struct obd_device *obd)
{
	int rc;
	struct ptlrpc_request *req;

	req = ptlrpc_prep_ping(obd->u.cli.cl_import);
	if (!req)
		return -ENOMEM;

	req->rq_send_state = LUSTRE_IMP_FULL;

	rc = ptlrpc_queue_wait(req);

	ptlrpc_req_finished(req);

	return rc;
}
EXPORT_SYMBOL(ptlrpc_obd_ping);

static int ptlrpc_ping(struct obd_import *imp)
{
	struct ptlrpc_request *req;

	req = ptlrpc_prep_ping(imp);
	if (!req) {
		CERROR("OOM trying to ping %s->%s\n",
		       imp->imp_obd->obd_uuid.uuid,
		       obd2cli_tgt(imp->imp_obd));
		return -ENOMEM;
	}

	DEBUG_REQ(D_INFO, req, "pinging %s->%s",
		  imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
	ptlrpcd_add_req(req);

	return 0;
}

static void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
{
	int time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;

	if (imp->imp_state == LUSTRE_IMP_DISCON) {
		int dtime = max_t(int, CONNECTION_SWITCH_MIN,
				  AT_OFF ? 0 :
				  at_get(&imp->imp_at.iat_net_latency));
		time = min(time, dtime);
	}
	imp->imp_next_ping = cfs_time_shift(time);
}

static inline int imp_is_deactive(struct obd_import *imp)
{
	return (imp->imp_deactive ||
		OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE));
}

static inline int ptlrpc_next_reconnect(struct obd_import *imp)
{
	if (imp->imp_server_timeout)
		return cfs_time_shift(obd_timeout / 2);
	else
		return cfs_time_shift(obd_timeout);
}

static long pinger_check_timeout(unsigned long time)
{
	struct timeout_item *item;
	unsigned long timeout = PING_INTERVAL;

	/* The timeout list is a increase order sorted list */
	mutex_lock(&pinger_mutex);
	list_for_each_entry(item, &timeout_list, ti_chain) {
		int ti_timeout = item->ti_timeout;

		if (timeout > ti_timeout)
			timeout = ti_timeout;
		break;
	}
	mutex_unlock(&pinger_mutex);

	return cfs_time_sub(cfs_time_add(time, cfs_time_seconds(timeout)),
					 cfs_time_current());
}

static bool ir_up;

void ptlrpc_pinger_ir_up(void)
{
	CDEBUG(D_HA, "IR up\n");
	ir_up = true;
}
EXPORT_SYMBOL(ptlrpc_pinger_ir_up);

void ptlrpc_pinger_ir_down(void)
{
	CDEBUG(D_HA, "IR down\n");
	ir_up = false;
}
EXPORT_SYMBOL(ptlrpc_pinger_ir_down);

static void ptlrpc_pinger_process_import(struct obd_import *imp,
					 unsigned long this_ping)
{
	int level;
	int force;
	int force_next;
	int suppress;

	spin_lock(&imp->imp_lock);

	level = imp->imp_state;
	force = imp->imp_force_verify;
	force_next = imp->imp_force_next_verify;
	/*
	 * This will be used below only if the import is "FULL".
	 */
	suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);

	imp->imp_force_verify = 0;

	if (cfs_time_aftereq(imp->imp_next_ping - 5 * CFS_TICK, this_ping) &&
	    !force) {
		spin_unlock(&imp->imp_lock);
		return;
	}

	imp->imp_force_next_verify = 0;

	spin_unlock(&imp->imp_lock);

	CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA, "%s->%s: level %s/%u force %u force_next %u deactive %u pingable %u suppress %u\n",
	       imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
	       ptlrpc_import_state_name(level), level, force, force_next,
	       imp->imp_deactive, imp->imp_pingable, suppress);

	if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
		/* wait for a while before trying recovery again */
		imp->imp_next_ping = ptlrpc_next_reconnect(imp);
		if (!imp->imp_no_pinger_recover)
			ptlrpc_initiate_recovery(imp);
	} else if (level != LUSTRE_IMP_FULL ||
		   imp->imp_obd->obd_no_recov ||
		   imp_is_deactive(imp)) {
		CDEBUG(D_HA, "%s->%s: not pinging (in recovery or recovery disabled: %s)\n",
		       imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
		       ptlrpc_import_state_name(level));
		if (force) {
			spin_lock(&imp->imp_lock);
			imp->imp_force_verify = 1;
			spin_unlock(&imp->imp_lock);
		}
	} else if ((imp->imp_pingable && !suppress) || force_next || force) {
		ptlrpc_ping(imp);
	}
}

static int ptlrpc_pinger_main(void *arg)
{
	struct ptlrpc_thread *thread = arg;

	/* Record that the thread is running */
	thread_set_flags(thread, SVC_RUNNING);
	wake_up(&thread->t_ctl_waitq);

	/* And now, loop forever, pinging as needed. */
	while (1) {
		unsigned long this_ping = cfs_time_current();
		struct l_wait_info lwi;
		long time_to_next_wake;
		struct timeout_item *item;
		struct list_head *iter;

		mutex_lock(&pinger_mutex);
		list_for_each_entry(item, &timeout_list, ti_chain) {
			item->ti_cb(item, item->ti_cb_data);
		}
		list_for_each(iter, &pinger_imports) {
			struct obd_import *imp =
				list_entry(iter, struct obd_import,
					   imp_pinger_chain);

			ptlrpc_pinger_process_import(imp, this_ping);
			/* obd_timeout might have changed */
			if (imp->imp_pingable && imp->imp_next_ping &&
			    cfs_time_after(imp->imp_next_ping,
					   cfs_time_add(this_ping,
							cfs_time_seconds(PING_INTERVAL))))
				ptlrpc_update_next_ping(imp, 0);
		}
		mutex_unlock(&pinger_mutex);

		/* Wait until the next ping time, or until we're stopped. */
		time_to_next_wake = pinger_check_timeout(this_ping);
		/* The ping sent by ptlrpc_send_rpc may get sent out
		 * say .01 second after this.
		 * ptlrpc_pinger_sending_on_import will then set the
		 * next ping time to next_ping + .01 sec, which means
		 * we will SKIP the next ping at next_ping, and the
		 * ping will get sent 2 timeouts from now!  Beware.
		 */
		CDEBUG(D_INFO, "next wakeup in " CFS_DURATION_T " (%ld)\n",
		       time_to_next_wake,
		       cfs_time_add(this_ping,
				    cfs_time_seconds(PING_INTERVAL)));
		if (time_to_next_wake > 0) {
			lwi = LWI_TIMEOUT(max_t(long, time_to_next_wake,
						cfs_time_seconds(1)),
					  NULL, NULL);
			l_wait_event(thread->t_ctl_waitq,
				     thread_is_stopping(thread) ||
				     thread_is_event(thread),
				     &lwi);
			if (thread_test_and_clear_flags(thread, SVC_STOPPING))
				break;
			/* woken after adding import to reset timer */
			thread_test_and_clear_flags(thread, SVC_EVENT);
		}
	}

	thread_set_flags(thread, SVC_STOPPED);
	wake_up(&thread->t_ctl_waitq);

	CDEBUG(D_NET, "pinger thread exiting, process %d\n", current_pid());
	return 0;
}

static struct ptlrpc_thread pinger_thread;

int ptlrpc_start_pinger(void)
{
	struct l_wait_info lwi = { 0 };
	struct task_struct *task;
	int rc;

	if (!thread_is_init(&pinger_thread) &&
	    !thread_is_stopped(&pinger_thread))
		return -EALREADY;

	init_waitqueue_head(&pinger_thread.t_ctl_waitq);

	strcpy(pinger_thread.t_name, "ll_ping");

	task = kthread_run(ptlrpc_pinger_main, &pinger_thread,
			   pinger_thread.t_name);
	if (IS_ERR(task)) {
		rc = PTR_ERR(task);
		CERROR("cannot start pinger thread: rc = %d\n", rc);
		return rc;
	}
	l_wait_event(pinger_thread.t_ctl_waitq,
		     thread_is_running(&pinger_thread), &lwi);

	return 0;
}

static int ptlrpc_pinger_remove_timeouts(void);

int ptlrpc_stop_pinger(void)
{
	struct l_wait_info lwi = { 0 };
	int rc = 0;

	if (thread_is_init(&pinger_thread) ||
	    thread_is_stopped(&pinger_thread))
		return -EALREADY;

	ptlrpc_pinger_remove_timeouts();
	thread_set_flags(&pinger_thread, SVC_STOPPING);
	wake_up(&pinger_thread.t_ctl_waitq);

	l_wait_event(pinger_thread.t_ctl_waitq,
		     thread_is_stopped(&pinger_thread), &lwi);

	return rc;
}

void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
{
	ptlrpc_update_next_ping(imp, 0);
}

void ptlrpc_pinger_commit_expected(struct obd_import *imp)
{
	ptlrpc_update_next_ping(imp, 1);
	assert_spin_locked(&imp->imp_lock);
	/*
	 * Avoid reading stale imp_connect_data.  When not sure if pings are
	 * expected or not on next connection, we assume they are not and force
	 * one anyway to guarantee the chance of updating
	 * imp_peer_committed_transno.
	 */
	if (imp->imp_state != LUSTRE_IMP_FULL ||
	    OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
		imp->imp_force_next_verify = 1;
}

int ptlrpc_pinger_add_import(struct obd_import *imp)
{
	if (!list_empty(&imp->imp_pinger_chain))
		return -EALREADY;

	mutex_lock(&pinger_mutex);
	CDEBUG(D_HA, "adding pingable import %s->%s\n",
	       imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
	/* if we add to pinger we want recovery on this import */
	imp->imp_obd->obd_no_recov = 0;
	ptlrpc_update_next_ping(imp, 0);
	/* XXX sort, blah blah */
	list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
	class_import_get(imp);

	ptlrpc_pinger_wake_up();
	mutex_unlock(&pinger_mutex);

	return 0;
}
EXPORT_SYMBOL(ptlrpc_pinger_add_import);

int ptlrpc_pinger_del_import(struct obd_import *imp)
{
	if (list_empty(&imp->imp_pinger_chain))
		return -ENOENT;

	mutex_lock(&pinger_mutex);
	list_del_init(&imp->imp_pinger_chain);
	CDEBUG(D_HA, "removing pingable import %s->%s\n",
	       imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
	/* if we remove from pinger we don't want recovery on this import */
	imp->imp_obd->obd_no_recov = 1;
	class_import_put(imp);
	mutex_unlock(&pinger_mutex);
	return 0;
}
EXPORT_SYMBOL(ptlrpc_pinger_del_import);

/**
 * Register a timeout callback to the pinger list, and the callback will
 * be called when timeout happens.
 */
static struct timeout_item *ptlrpc_new_timeout(int time,
					       enum timeout_event event,
					       timeout_cb_t cb, void *data)
{
	struct timeout_item *ti;

	ti = kzalloc(sizeof(*ti), GFP_NOFS);
	if (!ti)
		return NULL;

	INIT_LIST_HEAD(&ti->ti_obd_list);
	INIT_LIST_HEAD(&ti->ti_chain);
	ti->ti_timeout = time;
	ti->ti_event = event;
	ti->ti_cb = cb;
	ti->ti_cb_data = data;

	return ti;
}

/**
 * Register timeout event on the pinger thread.
 * Note: the timeout list is an sorted list with increased timeout value.
 */
static struct timeout_item*
ptlrpc_pinger_register_timeout(int time, enum timeout_event event,
			       timeout_cb_t cb, void *data)
{
	struct timeout_item *item, *tmp;

	LASSERT(mutex_is_locked(&pinger_mutex));

	list_for_each_entry(item, &timeout_list, ti_chain)
		if (item->ti_event == event)
			goto out;

	item = ptlrpc_new_timeout(time, event, cb, data);
	if (item) {
		list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
			if (tmp->ti_timeout < time) {
				list_add(&item->ti_chain, &tmp->ti_chain);
				goto out;
			}
		}
		list_add(&item->ti_chain, &timeout_list);
	}
out:
	return item;
}

/* Add a client_obd to the timeout event list, when timeout(@time)
 * happens, the callback(@cb) will be called.
 */
int ptlrpc_add_timeout_client(int time, enum timeout_event event,
			      timeout_cb_t cb, void *data,
			      struct list_head *obd_list)
{
	struct timeout_item *ti;

	mutex_lock(&pinger_mutex);
	ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
	if (!ti) {
		mutex_unlock(&pinger_mutex);
		return -EINVAL;
	}
	list_add(obd_list, &ti->ti_obd_list);
	mutex_unlock(&pinger_mutex);
	return 0;
}
EXPORT_SYMBOL(ptlrpc_add_timeout_client);

int ptlrpc_del_timeout_client(struct list_head *obd_list,
			      enum timeout_event event)
{
	struct timeout_item *ti = NULL, *item;

	if (list_empty(obd_list))
		return 0;
	mutex_lock(&pinger_mutex);
	list_del_init(obd_list);
	/**
	 * If there are no obd attached to the timeout event
	 * list, remove this timeout event from the pinger
	 */
	list_for_each_entry(item, &timeout_list, ti_chain) {
		if (item->ti_event == event) {
			ti = item;
			break;
		}
	}
	if (list_empty(&ti->ti_obd_list)) {
		list_del(&ti->ti_chain);
		kfree(ti);
	}
	mutex_unlock(&pinger_mutex);
	return 0;
}
EXPORT_SYMBOL(ptlrpc_del_timeout_client);

static int ptlrpc_pinger_remove_timeouts(void)
{
	struct timeout_item *item, *tmp;

	mutex_lock(&pinger_mutex);
	list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
		LASSERT(list_empty(&item->ti_obd_list));
		list_del(&item->ti_chain);
		kfree(item);
	}
	mutex_unlock(&pinger_mutex);
	return 0;
}

void ptlrpc_pinger_wake_up(void)
{
	thread_add_flags(&pinger_thread, SVC_EVENT);
	wake_up(&pinger_thread.t_ctl_waitq);
}